The invention relates to a system comprising a control apparatus for semiconductor switches of an inverter and to a method for actuating an inverter, in particular in a diagnostics operating mode for a connected DC link.
Electric and hybrid vehicles often have power electronics circuit components in the drive system between the traction battery and the electric machine which are generally in the form of DC link converters. In this case, a DC link is used as coupling element between the traction battery and an inverter which can be actuated in order to transfer electric power from the DC link to the electric machine.
Inverters can be in the form of, for example, a full-bridge circuit comprising a number of bridge branches, each having two semiconductor switches. In this case, the semiconductor switches in the bridge branches which are connected to a first output connection of the DC link are each referred to as high-side switches and the semiconductor switches in the bridge branches which are connected to the second output connection of the DC link are each referred to as low-side switches. In this case, for example, IGBT modules (insulated-gate bipolar transistors) with a diode connected back-to-back in parallel or MOSFETs (metal-oxide field-effect transistors) can be used as semiconductor switches.
In such systems, it is desirable to be able to check the voltage storage elements used in the DC link, such as DC link capacitors, for degradation effects owing to aging or overloading. Such degradation effects can under certain circumstances result in restrictions to the performance of the storage elements and, under certain circumstances, also to failure of the entire system.
The publication US 2005/0231171 A1 discloses an electric drive system comprising an electric motor, a pulse-controlled inverter and a DC link capacitor. The DC link capacitor can be discharged in a controlled manner via a corresponding switch operation of the pulse-operated inverter.